柱帽大板无梁楼盖冲切安全影响因素分析

Analysis of Influencing Factors on Punching-cutting Safety of Column Cap Plate Girderless Floor

柱帽大板无梁楼盖多起坍塌事故说明柱帽冲切安全是此种楼盖形式的设计关键。目前很多计算软件及设计人员仅考虑冲切净反力作用下的冲切计算,未考虑不平衡弯矩引起的冲切临界截面上的附加剪应力对柱帽冲切安全的影响。分析了不平衡弯矩对冲切安全的影响大小,结果显示不平衡弯矩的影响不容忽视,并建议了冲切系数的计算原则及其限制,以保证柱帽大板无梁楼盖的安全。

Multiple collapse accidents of large slab without beam floor with column cap indicate that the safety of column to column cap punching is the key to the design of this kind of floor.At present,many structural design software and designers only consider the calculation of punching safety under the action of net punching reaction,and do not consider the impact of additional shear stress on the critical section of punching safety of the column cap caused by unbalanced bending moment.In this paper,the influence of unbalanced moment on shear safety is analyzed,and the result shows that the influence of unbalanced moment on shear safety cannot be ignored.